net: fsl/fman: treat all RGMII modes in memac_adjust_link()

Treat all internal delay variants the same as RGMII.

Signed-off-by: Madalin Bucur <madalin.bucur@oss.nxp.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>